In the diffusion transfer photographic process, compounds having a dye compound moiety connected with a moiety for changing diffusibility are employed as dye providing compounds. The moiety for changing diffusibility means a moiety having a function capable of changing diffusibility of the dye providing compound before and after development processing under alkaline conditions. Dye providing compounds are classified into dye releasing type dye providing compounds and dye fixing type dye providing compounds depending on the function of the moiety for changing diffusibility.
Dye releasing type dye providing compounds are originally non-diffusible per se and provide diffusible dyes in correspondence or counter-correspondence to development by the function of the moiety for changing diffusibility as a result of development processing under alkaline conditions. Many dye releasing type dye providing compounds are known and are mainly divided into those having a negative acting mother skeleton which releases a dye upon oxidation and those having a positive acting mother skeleton which releases a dye upon reduction.
Examples of the negative acting dye providing compounds are described, for example, in JP-A-48-33826, JP-A-49-114424, JP-A-49-126331, JP-A-49-126332, JP-A-50-115528, JP-A 51-104343 (the term "JP-A" as used herein means an "unexamined published Japanese patent application"), U.S. Pat. Nos. 3,928,312, 3,931,144 and 3,954,476, and Research Disclosure, Vol. 130, No. 13024 (February, 1975).
Examples of the positive acting dye providing compounds include those having a moiety containing an electron acceptive center and an intramolecular nucleophilic displacement reaction center in a compound capable of releasing a photographic reagent upon a nucleophilic displacement reaction in the molecule after being reduced as described, for example, in U.S. Pat. Nos. 4,139,389, 4,139,379 and 4,564,577, JP-A-59-185333 and JP-A-57-84453; those having a moiety containing an electron acceptive quinoid center in a compound capable of releasing a photographic reagent upon an intramolecular electron transfer reaction after being reduced and a carbon atom bonding the quinoid center and the photographic reagent as described, for example, in U.S. Pat. No. 4,232,107, JP-A-59-101649, Research Disclosure, No. 24025 (1984), and JP-A-61 88257; those having a moiety containing an aryl group substituted with an electron attractive group in a compound capable of releasing a photographic reagent by cleaving the single bond after being reduced and an atom (sulfur atom, carbon atoms, or nitrogen atom) bonding the aryl group and the photographic reagent as described, for example, in West German Patent Application (OLS) No. 3,008,588, JP-A-56-142530, and U.S. Pat. Nos. 4,343,893 and 4,619,884; those having a moiety containing a nitro group in a nitro compound capable of releasing a photographic reagent after receiving an electron and a carbon atom bonding the nitro group and the photographic reagent as described, for example, in U.S. Pat. No. 4,450,223; and those having a moiety containing a dieminaldinitro moiety in a dinitro compound capable of .beta.-releasing a photographic reagent after receiving an electron and a carbon atom bonding the dieminaldinitro moiety and the photographic reagent as described, for example, in U.S. Pat. No. 4,609,610.
Further, compounds of improved characteristics which contain a bond representatively illustrated by a bond of N--X (wherein X represents an oxygen atom, a sulfur atom or a nitrogen atom) and an electron attractive group in their molecules as described, for example, in European Patent 220,746A, U.S. Pat. No. 4,783,396, Kokai-Giho No. 87-6199, JP-A-62-215270, JP-A-62-244048, JP-A-63-201653, JP-A-63-201654, JP-A-63-271344, JP-A-63-271341 and JP-A-1-26842 are known.
Dye fixing type dye providing compounds are compounds which are originally diffusible or can release diffusible dyes and become non-diffusible or stop releasing diffusible dyes by the function of the moiety for changing diffusibility as a result of development processing. Examples of the dye fixing type dye providing compounds are described, for example, in JP-A-51-63618 and JP-A-53-35533.
On the other hand, with respect to dye compound moieties in the dye providing compounds, many investigations with respect to their hue, transferability, or fastness, etc. have been made. Reports on yellow dye providing compounds are illustrated in U.S. Pat. Nos. 3,597,200, 3,309,199, 4,013,633, 4,245,028, 4,156,609, 4,139,383, 4,195,992, 4,148,641, 4,148,643 and 4,336,322, JP-A-51-114930, JP-A-56-71072, Research Disclosure, No. 17630 (1978) and ibid., No. 16475 (1977).
As the result of these investigations, large improvements have been made in hue, transferability, fastness and stability of hue. However, it cannot be said that these compounds are satisfactory with respect to tolerance or the degree of freedom for designing and preparing of photographic element.
Particularly, when taking the stability of the transferred image into consideration, they do not have sufficient properties in both light fading and dark fading. Therefore, more stable dye compounds moieties have been desired. It is especially desired to improve the stability of color image, because there is the possibility of wide spread usage of the diffusion transfer process if improvements in the stability of the dye can be obtained.
Heat-resistivity and light-fastness greater than those requested for ordinary photographic images obtained by the diffusion transfer process are necessary for dyes for forming pattern images in color filters. The development of a stable dye would increase the possibility of the practical application thereof to such a field.